Pressure-induced localisation of the hydrogen-bond network in KOH-VI

Andreas Hermann, Malcolm Guthrie, Richard J. Nelmes, John S. Loveday

Research output: Contribution to journalArticlepeer-review

Abstract

Using a combination of ab initio crystal structure prediction and neutron diffraction techniques, we have solved the full structure of KOH-VI at 7 GPa. Rather than being orthorhombic and proton-ordered as had previously be proposed, we find that this high-pressure phase of potassium hydroxide is tetragonal (space group I4/mmm) and proton disordered. It has an unusual hydrogen bond topology, where the hydroxyl groups form isolated hydrogen-bonded square planar (OH)4 units. This structure is stable above 6.5 GPa and, despite being macroscopically proton-disordered, local ice rules enforce microscopic order of the hydrogen bonds. We suggest the use of this novel type of structure to study concerted proton tunneling in the solid state, while the topology of the hydrogen bond network could conceivably be exploited in data storage applications based solely on the manipulations of hydrogen bonds. The unusual localisation of the hydrogen bond network under applied pressure is found to be favored by a more compact packing of the constituents in a distorted cesium chloride structure.
Original languageEnglish
Pages (from-to)244706
Number of pages10
JournalThe Journal of Chemical Physics
Volume143
Issue number24
DOIs
Publication statusPublished - 29 Dec 2015

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